ostripper said:Show off...
Isn't that what this is all about?
ostripper said:
Even andy likes zeners,MJl..Fire them fa2's up and tell me how they sound..
There's no accounting for taste, I guess...
Zeners not required.
Gee OS, I have only built one. I haven't had the opportunity to hook it up to a speaker and actually listen. It has stiff competition in my Patchwork. Be it ever so humble, it does sound sublime
I have finished the first permanent version of my topology/design rip Abomination! Right off the starting blocks it is solid.
Amazingly stable with just two 15pF caps. I have used my LM394 supermatched pair for the differential input. This will be an amp to be reckoned with!
Go ahead, I dare you, ask me for more details
Did you get your parts? I'm doing my best to keep your thread alive here but we need to see some pics from you...listining impressions, that sort of thing.
MJL21193 said:
Either I miss-worded or someone misread.
I would not say that many casodes are cascoding on the emitter side.
They are on the input pair collector side.
What can differ is where the cascode baseside is connected = refered to.
So, from the context I thought this is obvious what can be discussed.
- The Federico Paoletti (Donizetti, Puccini, Classe) just have the bias connected via one resistor to the power supply.
.... As could be seen in my attachment from one of his commercial Classe Power Amps.
- Some put a zener or resistor divider to GND.
- We can use resistor dividers between pos neg supply.
- In MJL21193 case, he uses one current source from supply
and then one resistor connected to emitter side of LTP.
Plenty many ways to set the working voltage level for Cascodes!!I posted Paoletti simple high value resistor, because it was an original way to do it.
And as he surely is experienced .. I think it can not be too bad. Maybe even good?
--------
Federico Paoletti unsual way:
http://www.diyaudio.com/forums/attachment.php?postid=1680228&stamp=1228851835
lineup said:
I posted Paoletti simple high value resistor, because it was an original way to do it.
And as he surely is experienced .. I think it can not be too bad. Maybe even good?
--------
Federico Paoletti unsual way:
http://www.diyaudio.com/forums/attachment.php?postid=1680228&stamp=1228851835
Before posting totally incompetent designs and attaching someone's name to them, you should be absolutely sure the schematic represents the actual design and the person stated is the actual designer.
At any rate, a conventional cascode input stage has almost no advantages. Hugh posted a bootstrapped cascode idea earlier, which can be verified to reduce input stage distortion. But in order to see that reduction, other aspects of the design must be improved. This might involve cascoding the VAS to reduce its distortion. But when you get into this area, the "frugal" concept is lost.
that looks like your T-trak dohiggie, to rich for my blood.
I just can't keep up with you guys ,not wealthy enough.
1-2 amps a month, can't spend more than 40-50$ or cuts into
food.
Lots of industrial junk around,heatsinks ,trafo's,consumer
items. Not 1 purchase of media/software in 5 years. Download/
rip everything.
Strange how I obtained my last E-waste, had to wup a
crackhead who wanted the scrap metal for drugs.
Between walmart and recession half of knoxville is a boarded up
ghetto with neferious charactors everywhere,The only way
I can even participate in this forum is my skill of repair.
2 19" flat screens,1 coreduo w/3TB HDD's,all the cards...from
the dumpster...America is a "banana republic"
Well, enough of that, parts are (50ms ups web page) parts
are in tenn.,will be here thurs. morn. Will be blasting it
thursday night...
OS
jaycee said:
Your board shows me that it's doable
Sometimes I just have to
ostripper said:
They were 80 cents a piece...
ostripper said:
I just can't keep up with you guys ,not wealthy enough.
1-2 amps a month, can't spend more than 40-50$ or cuts into
food.
Well, enough of that, parts are (50ms ups web page) parts
are in tenn.,will be here thurs. morn. Will be blasting it
thursday night...
OS
Tough times my friend. I'm far from wealthy - been flat broke most of my life but I got rid of those expensive things (wives) and now have a few pennies to rub together.
Mouser shipping that slow? I order from Digikey in Minnesota, it goes from there to Louisville then on a plane to Toronto. Truck brings it local and a van has it at my door 24 hours after I have completed the order on the internet. It's truly mind boggling.
ostripper said:
They were sold off from Arrow. They weren't lead free so I guess they had to go. My problem is that I only bought 25 of each.
You are buying the wrong drivers. 2SC4793 and 2SA1837 are less than a buck here, so they're like 60-70 cents down there. For drivers, they don't come much better.
$8 for shipping - UPS right to the door. No minimum order.
Attachments
that amp looks like an electronic centipede.
BTW..FA2 will be done in hours...they don't look too bad considering being TOTALLY hand made.
An externally hosted image should be here but it was not working when we last tested it.
I'm fitting the vas's as I type (cut off aluminum real estate sign)
Mouser sent me the original 1845's.. good matching
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
23 out of 25 read within 2-3 Hfe... whoh, not bad for .09c trannies.
Amp tonight...
Os
ostripper said:
Many legs...
ostripper said:
Hand made is worth more
Being in construction, I get lots of scrap aluminum, steel and stainless steel so it doesn't cost me a cent (either
)You had to buy the 1845's? I harvested about 30 of these from a single Kenwood receiver that I bought a Goodwill for $2. You are not being frugal enough!
ostripper said:Now I get to show off, right before the bench
Looks good, sounds...?
Whooohoo.. NO smoke..
Initial offset of 2mV, (tiny tweak to trimmer later for picoV range)
Interesting how EXTREMELY close the real thing is to the
simulation.(VAS current 6.2ma vs. 6ma sim ,LTP current 1.9 vs.
1.8 sim) This could be a PS thing, but the hell with those who
"diss the sim" for they are unenlightened.
I'm only running in driver mode (mje15032/33's running headphones) but sound is clear as a bell.
After setting bias at OP EF for 1V (under biased),flicking a lighter under the Vbias tranny (confirm it's proper function)
I can place the OPS for full power testing.
OS
And safe ,too. I always run in "headphone mode" it is
very wise (frugal).
Many advantages to this method..1. you can hear it, 2.let
onboard components stabilize to check for temp.
,offsetscurrents, etc. 3. definitely saves on OP devices as you do
not subject them to a untested amp.
Many here just "hook it up" and cross their fingers..
then cry in forum that they smoked their "burning amp". Poor
wasim in Quasi's amp thread smoked a dozen 4$ IRF's and
I wish I had them to play with..what a waste..
OS
headphones method
yes, i have used this.
once i did not use any output capacitor
and so my great Sony Fontopia earphones was burnt and destroyed.
Regarding listening testing, using headphones at the amplifier output
resembles to a doctor listening to your heartbeat, in a stetoscope.
And this gives a better sound quality and judgement, than using speakers
which have a magnitude higher distortion.
Besides, when listening through loudspeakers, your room will be a part of the performance, too.
yes, i have used this.
once i did not use any output capacitor
and so my great Sony Fontopia earphones was burnt and destroyed.
Regarding listening testing, using headphones at the amplifier output
resembles to a doctor listening to your heartbeat, in a stetoscope.
And this gives a better sound quality and judgement, than using speakers
which have a magnitude higher distortion.
Besides, when listening through loudspeakers, your room will be a part of the performance, too.
ostripper said:
Then I play music BEFORE placing headphones on
Chicken!
I took the time to build a variable power supply that goes from 5 to 30V. I always start a new design on 5 volts to see if there is a fault. The power supply has a digital ammeter to tell instantly if there is a heavy draw on the power.
I have been meaning to finish a switched attenuator for use in testing my amps with RMAA. This would be handy if it had a headphone jack as well. That way I could listen to a complete amp running at normal power.
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